HI everybody! 
  
This can happen because of special charactersm in the name. 
  
It's often a "." (point) in teh name that makes the game frezzing. It also happened to me my mouse acted like crazy!It began ointing at the ground or at the sky. Or even worse: I was stuck in the ground. 
  
So check the player's name and see if it contains points or dashes or smthg like that. 
  
  
Hope it heleped! 
  
Cheers 
  
M@C~Oner